On Oct 25, 2009, at 1:25 PM, Marius Strobl wrote:
>> Do you have a simple test case demonstrating the need for
> I-cache synchronisation?
I typically use GDB. If breakpoints aren't being hit or
next isn't behaving correctly, you typically have an
I-cache problem. If you get to run GDB, you probably
already know whether it's needed, because processes
tend to die with random signals at startup when the
architecture needs explicit I-cache coherency logic
and the kernel doesn't have it. A special case I would
say is executing from a memory disk. The I/O path
contains bcopy() operations, which dirty the D-cache
and trigger I-cache coherency bugs pretty well.
I didn't have issues with that on my Netra, so I didn't
implement pmap_sync_icache for sparc64. This is not to
say that it's absolutely not needed, just that GDB didn't
expose problems. If sparc64 has some of the same kluges
powerpc had, then I-cache coherency is handled in some
other (most likely a sub-optimal) way.
FYI,
--
Marcel Moolenaar
xcllnt at mac.com